Match List-I with List-II
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List-I |
List-II |
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(A) Mathematical expression for rate of reaction |
(I) Rate constant |
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(B) Rate of reaction for zero order reaction is equal to |
(II) Rate law |
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(C) Unit of rate constant for zero order reaction is same as that of |
(III) Order of slowest step |
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(D) Order of a complex reaction is determined by |
(IV) Rate of reaction |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-II, B-I, C-IV, D-III
The rate law expresses the rate of a reaction in terms of the molar concentrations of the reactants, each raised to a power: Rate = k[A]x[B]y. The sum x + y is the order, and k is the rate constant. Each of the four items is a consequence of this expression.
(A) Mathematical expression for rate of reaction — This matches (II) rate law. The rate law is the expression Rate = k[A]x[B]y found by experiment.
(B) Rate of reaction for zero order reaction is equal to — This matches (I) rate constant. For a zero order reaction the concentration term has power 0:
\( \text{Rate} = k[\mathrm{A}]^0 = k \)
(C) Unit of rate constant for zero order reaction is same as that of — This matches (IV) rate of reaction. Since Rate = k for a zero order reaction, both have the unit mol L−1 s−1.
(D) Order of a complex reaction is determined by — This matches (III) order of slowest step. A complex reaction takes place in several elementary steps; the slowest step is rate-determining, so the rate law, and hence the order, is that of the slowest step.
Shortcut: for a zero order reaction Rate = k, so B-I; only Option (3) has B-I.
NCERT (2026-27 edition):
Rate Expression and Rate Constant – “… The equation like (3.4), which relates the rate of a reaction to concentration of reactants is called rate law or rate expression. Thus, rate law is the expression in which reaction rate is given in terms of molar concentration of reactants with each term raised to some power, which may or may not be same as the stoichiometric coefficient of the reacting species in a balanced chemical equation.”
Molecularity of a Reaction – “… Similarly, the overall rate of the reaction is controlled by the slowest step in a reaction called the rate determining step.”